Year	per 1,000
1990	2.401772647342447
1991	2.346898555860724
1992	2.2614972675662774
1993	2.1920601631183136
1994	2.185435254909405
1995	2.1269025924360796
1996	2.0857719213187425
1997	2.0580482091116457
1998	2.0379645711494363
1999	2.016956511455824
2000	1.9774215907707706
2001	1.9545402048968723
2002	1.9319790005407294
2003	1.9090693226267812
2004	1.9023537032290245
2005	1.890321266968326
2006	1.852540792540792
2007	1.830816321475458
2008	1.8003028675759853
2009	1.752315638762528
2010	1.7223407112036464
2011	1.7089348413990948
2012	1.6436799692147497
2013	1.6215286190187765
2014	1.5640404422902152
2015	1.522466044078057
2016	1.5052817819352857
2017	1.6082342799933516
2018	1.4189416193652837
2019	2.132144250357592
2020	1.3689707222376293
2021	1.346735935063853
2022	1.3108999725581747